This invention concerns an improved process for hydrating cyclohexene to cyclohexanol employing perfluorosulfonic acid polymer as the catalyst.
The following publications represent the state of the art for hydrating olefins to alcohols: GB No. 2,082,178A discloses a process for hydrating C.sub.2 to C.sub.6 olefins in the presence of perfluorosulfonic acid polymer as catalyst. British Pat. No. 918,406 discloses a process for making cyclohexanol from cyclohexene in the presence of a conventional sulfonated polystyrene polymer.
Other publications that disclose olefin hydration include the following: U.S. Pat. No. 4,358,626 (reaction in presence of oxy acid or lactone); U.S. Pat. No. 4,340,769 (sulfonated styrene-divinylbenzene catalyst, C.sub.2 to C.sub.5 olefin); U.S. Pat. No. 4,065,512 (isobutene); U.S. Pat. No. 4,424,388 (reaction in presence of glycol diether); U.S. Pat. No. 4,080,391 (sulfonic acid catalyst); GB 2,075,019A (methyl t-butyl ether from isobutylene and methanol); and Research Disclosure, 19515, July 1980 (t-butanol from isobutylene and water).
Cyclohexanol is an intermediate in the preparation of adipic acid which is employed principally in the manufacture of nylon. Cyclohexene, the starting reactant of this process, has several interesting characteristics that distinguish its behavior from that of other lower olefins including straight chain olefins such as propylene and the like. For instance, thermodynamic calculations show that hydration of cyclohexene is much less favored than hydration of propylene. It follows, then, that one skilled in the art would expect cyclohexene to be much more difficult to hydrate than propylene and other lower straight chain olefins.